Many different kinds of lightweight armor systems are known and are currently being used in a wide range of applications, including, for example, aircraft, light armored vehicles, and body armor systems, wherein it is desirable to provide protection against armor piercing, explosive and chemical weapons. While early lightweight armor systems for such threats tended to rely on a single layer of a hard and brittle material, such as a ceramic material, it was soon realized that the effectiveness of the armor system could be improved considerably if the ceramic material were affixed to or “backed up” with an energy absorbing material, such as high strength Kevlar fibers. The presence of an energy absorbing backup layer functions to catch the fragments of an incoming projectile but without significantly reducing the spallation of the ceramic caused by impact of the projectile.
Testing has demonstrated that such multi-layer armor systems tend to stop projectiles at higher velocities than do the ceramic materials when utilized without the backup layer. While such multi-layer armoring systems are being used with some degree of success, they are not without their problems. For example, difficulties are often encountered in creating a multi-hit capability armor with multi-layered material structure having both sufficient mechanical strength and ballistic shock resistance as well as sufficient bond strength at the layer interfaces.
Partly in an effort to solve the foregoing problems, armor systems have been developed in which a “graded” ceramic material having a gradually increasing dynamic tensile strength and energy absorbing capacity is sandwiched between the impact layer and the backup layer. An example of such an armor system is disclosed in U.S. Pat. No. 3,633,520 issued to Stiglich and entitled “Gradient Armor System”.
The armor system disclosed in the foregoing patent comprises a ceramic impact layer that is backed by an energy absorbing ceramic matrix having a gradient of fine metallic particles dispersed therein in an amount from about 0% commencing at the front or impact surface of the armor system to about 0.5 to 50% by volume at the backup material.
Despite these advances, the need remains for an improved, more optimized lightweight composite armor which has the attributes of rigidity, strength, low density, impact resistance, and ease and favorable cost of manufacturing. As such, a need has developed for an encapsulated ceramic armor material that optimizes ballistic performance and may be manufactured in a repeatable, predictable way.